NMR_SPECTROSCOPY

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NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY:

NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY

VIJAYA INSTITUTE OF PHARMACEUTICAL SCIENCES FOR WOMEN Enikepadu, Vijayawada-521108:

VIJAYA INSTITUTE OF PHARMACEUTICAL SCIENCES FOR WOMEN Enikepadu, Vijayawada-521108 NUCLEAR MAGNETIC RESONANCE (NMR) SPECTROSCOPY presented by MD Jaha Sultana M. P harmacy (Pharmaceutics) 137N1S0308 Under the guidance of: Mr. Chaitanya Prasad Meher , M . Pharm Department of Pharmaceutical Analysis

CONTENTS:

CONTENTS INTRODUCTION HISTORY PRINCIPLE INSTRUMENTATION PARAMETERS EFFECTING NMR APPLICATIONS LIMITATIONS CONCLUSION

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SPECTROSCOPY It is an method used to study the light as a function of length of the wave that has been emitted, reflected through solid, liquid or gas. (or) Study of interaction of electromagnetic radiation with matter. . INTRODUCTION

NMR SPECTROSCOPY:

NMR SPECTROSCOPY NMR is a spectroscopy technique which is based on the absorption of Electromagnetic radiations in a radio frequency region 4 to 900 MHz by nuclei of atoms in the presence of magnetic field. W hen proton (hydrogen) is studied then it is called as proton magnetic resonance. W hen other nuclei like 13 C, 9 F, 35 Cl etc. are studied then it is called as NMR. Nuclei with odd mass number only gives NMR spectra i.e 1 H, 13 C, 9 F, 35 Cl etc. Because they have asymmetrical charge distribution.

HISTORY:

NOBEL PRIZES 1952 Physics Bloch (Stanford), Purcell (Harvard) "For their development of new methods for nuclear magnetic precision measurements and discoveries in connection there with " "For his contributions to the development of the methodology of high resolution nuclear magnetic resonance (NMR) spectroscopy" "For his resonance method for recording the magnetic properties of atomic nuclei" 1991 Chemistry Ernst (ETH) 1944 Physics Rabi (Columbia) HISTORY

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2002 Chemistry Wüthrich (ETH ) "For his development of nuclear magnetic resonance spectroscopy for determining the three-dimensional structure of biological macromolecules in solution" 2003 Medicine Lauterbur (University of Illinois in Urbana), Mansfield (University of Nottingham) "For their discoveries concerning magnetic resonance imaging"

PRINCIPLE:

A nucleus with an odd mass or an odd atomic number possess a nuclear spin, due to spinning a magnetic field is generated along the axis. W ithout externally applied magnetic field, the nuclear spins are random in directions. But when externally magnetic field is applied, the nuclear align themselves either parallel and antiparallel. PRINCIPLE

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T he nuclei spins on its own axis and a magnetic moment is created, resulting in a precessional orbit, with a frequency called precessional frequency (GROUND STATE). When energy in the form of radio frequency is applied and is equal to precessional frequency, then the transition of protons from lower energy to higher energy take places. NMR signals is recorded.

NMR SPECTRUM:

NMR SPECTRUM T he NMR spectra is a plot of, "intensity of NMR signals Vs frequency (magnetic field)".

SCHEMATIC NMR SPECTROMETER:

SCHEMATIC NMR SPECTROMETER

INTRUMENTATION:

Sample Holder : Glass tube with 8.5cm long and 0.3cm diameter. Permanent Magnet : It provide homogenous magnetic field at 60-100 MHz. Magnetic Coils : These coils induced magnetic field when current flow through them. Sweep Generator : To produce the equal amount of magnetic field passed through the sample. Radio Frequency : A radio frequency transmitter coil that Generator produce a short powerful pulse of radio waves. Radio Frequency : A radio receiver coil that detects radio Receiver frequency emitted as nuclei relax to a lower energy levels. Read Out : A computer that analyses and record data. INTRUMENTATION

SOLVENT SYSTEM USED IN NMR:

SOLVENT SYSTEM USED IN NMR A substance which is free of protons should be used as solvent . i.e ., it should not give of its own absorption in NMR spectrum. I t should be capable of dissolving atleast 10% of substance. E xamples: CCl 4 - Carbon Tetrachloride CS 2 - Carbon Disulfide CDCl 3 - Deuteriochloroform C 6 D 6 - Hexa Deuteriobenzene D 2 O - D euterium O xide

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Chemical Shift Spin Spin Coupling Coupling Constant ( J ) PARAMETERS EFFECTING NMR SPECTROSCOPY

CHEMICAL SHIFT :

CHEMICAL SHIFT A chemical shift is defined as the difference in parts per million (ppm) between the resonance frequency of the observed proton and tetramethylsilane (TMS) hydrogens. TMS is most compound reference compound in NMR it is set at τ = 0 ppm.

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S hielding : Shifts the absorption upfield . D eshielding : Shifts the absorption downfield.

FACTORS AFFECTING CHEMICAL SHIFT:

FACTORS AFFECTING CHEMICAL SHIFT I nductive effect (or) electronegitive groups E.g.: CH 3 CH 2 F and CH 3 CH 2 Cl V ander waals deshielding A nisotropic effect H ydrogen bonding

SPIN SPIN COUPLING:

SPIN SPIN COUPLING T he interaction between the spins of neighbouring nuclei in the molecule may causes splitting of NMR. T his is called as spin spin coupling.

RULES OF SPIN SPIN COUPLING::

RULES OF SPIN SPIN COUPLING: Chemically equivalent nuclei do not show spin-spin coupling. Eg: CH 4 , CH 3 -CH 3 Only non equivalent protons couple. P rotons on adjacent carbon normally couple. P rotons separate by four or more bonds will not couple. Multiplicity Intensity Ratio Singlet (s) 1 Doublet (d) 1:1 Triplet (t) 1:2:1 Quartet (q) 1:3:3:1 Quintet 1:4:6:4:1 Sextet 1:5:10:10:5:1 Septet 1:6:15:20:15:6:1

COUPLING CONSTANT (J):

COUPLING CONSTANT (J) T he distance between the peaks in the multiplet is a measure of splitting effect known as coupling constant. E xpressed in Hz. C oupling constant is a measure of spin spin coupling.

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1. QUALITATIVE ANALYSIS: The number of main NMR signals should be equal to number of equivalent protons in unknown compounds. Chemical shift indicates types of H-atoms present. E.g: methylene, methyl, ethers etc. Spin-spin splitting or multiplicity reveals possible arrangement of groups in molecule. From the area of peaks; number of hydrogen nuclei present in each group can be found out. APPLICATIONS

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2. QUANTITATIVE ANALYSIS: It has been used to determine molar ratio of components in a mixture. I t does not require pure compound. 3. KETO-ENOL TAUTOMERISM: E.g.: Acetyl acetone

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4. DETERMINATION OF H-BONDING: Used to study H-bonding in metal chelates as well as in organic compounds.

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5. DETERMINATION OF AROMATICITY:

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6. DETERMINATION OF ELECTRONEGATIVE ATOM: E.g.: F, O & N from left to right the downward shift decreases. 7. DETERMINATION OF STRUCTURE: E.g.: 1. Fluorine atoms in SOF 4 are equivalent. 2. HF 2 has linear structure.

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8. IDENTIFICATION OF STRUCTURAL ISOMERS: E.g.: 9. DETERMINATION OF GEOMETRICAL ISOMERS: Different chemical shift values and their coupling constant. cis form J value 7 – 12 trans form J value 13 - 18

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10. STUDY OF ISOTOPES OTHER THAN PROTONS: E.g.: Fluorine and Phosphorous. The 31 P bearing spin number ½ exhibits sharp NMR peaks, with a resonance frequency of 24.3 MHz at 1400 guass . 11. ESTIMATION OF OPTICAL PU RITY:

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12. DIAGONSIS OF ERRORS IN METABOLISM: Errors like P henyl ketonuria, M aple's urine syndrome 13. NMR IN MEDICAL SCIENCES: Magnetic resonance imaging (MRI) in medical diagnosis and magnetic resonance microscopy in research. 14. OTHER APPLICATIONS: Chemical manufacturing industry Biological and biochemical research Food industry Pharmaceutical development and production Agrochemical development and production Polymer industry

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It is less sensitive. Due to more than one hydrogen atom overlap spectra occurs in which make difficult to analyze the desired spectra. M olecular weight of compound cannot be determined. E xpensive. L arge amount of sample is required. LIMITATIONS

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It is most powerful technique used for the examination of nuclear structure. S imple sample preparation prior to actual measurement. A wide variety of organic and inorganic compounds can be analyzed. D oes not require reference standard of the component U sed for identification of compounds using fingerprint technique. ADVANTAGES

CONCULSION:

CONCULSION T he power of NMR is to "visualize" how molecules interact, in the context of molecule dynamic and three dimensional structure make it unique for studying the mechanistic and functional properties of proteins and nuclei acids. N o sample preparation, t ha t saves time and effort. Cal ibration is easy and straight forward, delivering accurate and precise results. Over the past few decades, NMR has a very dynamic and exciting area. So, I truly believe that this is a trend that will stay for decades to come.

REFERENCES:

U. Holzgrabe, I. Wawer, B. Diehl; A text book of NMR spectroscopy in pharmaceutical analysis; Page. N o: 277-279. B. K. Sharma; A text book of instrumental methods of chemical analysis ; Page. N o:619 - 736. Gurdeep R. Chatwal, Sham K. Anand ; A text book of instrumental methods of chemical analysis; Page. N o: 2.185-2.220 www.slideshare.net/ solairajananant /nmr-spectroscopy-13887430‎ jghx.snnu.edu.cn/ yqfx / upfile /15.ppt‎ orgchem.colorado.edu/Spectroscopy/ nmrtheory /THSNMR.ppt‎ chemistry.csudh.edu/faculty/ jim /nmr.ppt‎ www.physik.uzh.ch/groups/ aegerter /teaching/BIO253/bio253_3.ppt‎ en.wikipedia.org/wiki/ Nuclear_magnetic_resonance_spectroscopy www.chemistry.msu.edu/faculty/ reusch / VirtTxtJml /.../ nmr /nmr1.htm‎ www.cis.rit.edu/ htbooks / nmr /‎ www.sciencedirect.com/science/ bookseries /00664103‎ phy.ntnu.edu.tw/~ cchen /class/biophysics/NMR-1_basic.pdf‎ http ://en.wikipedia.org/wiki/Nuclear_magnetic_resonance_Applications http://sydney.edu.au/science/chemistry/~long/applications.html REFERENCES